High-resolution electric field sensor based on whispering gallery modes of a beam-coupled dielectric resonator

This paper presents a high-resolution optical sensor concept for electric field detection. The sensing element is a coupled dielectric microsphere-beam. The material for both the sphere and the beam is polydimethylsiloxane (PDMS). The measurement principle is based on the whispering gallery optical mode (WGM) shifts of the microsphere. The external electric field imposes an electrtrostriction force on the dielectric beam, deflecting it. The beam, in turn compresses the sphere causing a shift in its WGM. An analysis is carried out along with preliminary experiments. Results show that electric fields as small as ∼ 100 V/m can be detected using a 300 μm diameter sphere.